About

"Wallpaper" is the term used in Microsoft Windows before Windows Vista (where it is called the Desktop "Background"), while Mac OS X calls it a "desktop picture".

Background also desktop picture is an image used as a background of a graphical user interface on a computer or mobile device. On a computer it is usually for the desktop, while for a mobile phone it is usually the background for the 'home' or 'idle' screen.
Image is a two-dimensional picture, that has a similar appearance to some subject.